LA JOLLA, Calif. - Fifteenth-ranked UC San Diego scored three runs in the bottom of the seventh and held on to beat Sonoma State, 3-0, in the opening game for both teams of the 2014 NCAA Division II Baseball Championship West Regional Thursday night at Triton Ballpark.

UCSD is serving as host for the six-team, double-elimination tournament.

Four Triton arms combined on a five-hit shutout, with junior left-hander Trevor Scott (7-2) starting and going the first 7.1 frames in a sparkling effort. He matched his season high with seven strikeouts, scattering three singles and a pair of walks.

Redshirt freshman rightfielder Brandon Shirley’s first-pitch, two-run triple to the gap in left center put UCSD on the board in the seventh after a one-out walk and a single ahead of him. Erik Lewis’ single two pitches later determined the final margin.

Senior closer Scott Zeman saw Sonoma State load the bases after getting the initial out of the ninth, but a strikeout and a flyout capped the victory and his ninth save of 2014.

Top seed UCSD (36-14) will take on Cal Poly Pomona, a 5-3 loser in Thursday’s first game, at 3 p.m. on Friday, with the fourth-seeded Broncos facing elimination. Sixth seed Sonoma State faces an elimination game with No. 5 seed Dixie State to lead off Friday's activity at 11 a.m. Second-seeded Chico State, a 5-4 winner over Dixie State Thursday, will meet third-seeded California Baptist at 7 p.m. in the winner's bracket.

True freshman centerfielder Jack Larsen worked the count full and drew the key one-out walk in the big seventh for UCSD. Following a first Sonoma State pitching change, Garrett Tuck singled up the middle. Shirley then pounced on Aaron Gillis’ first offering for his first collegiate triple. Lewis’ single scored him easily.

Meanwhile, Scott was dealing, retiring 11 straight Seawolves between a two-out hit-by-pitch in the fourth and finally a perfect one-out bunt single by leadoff man Jourdan Weiks in the eighth. That stretch included a nine-pitch 1-2-3 sixth. Scott retired the side in order in the second, fifth and seventh as well.

Scott exited shortly after Weiks’ bunt single, as he walked Daniel Caresio. Left-handed specialist Chad Rieser came on and did his job, inducing a fielder’s choice groundout to leave men at the corners. David Hart replaced Rieser and got a flyout.

UCSD put the leadoff man on base for the first and only time in the sixth as Shirley chopped a first-pitch single over the third baseman. The Tritons eventually loaded the bases with two away through an infield error and a walk, but grounded out.

Shirley and Lewis each had a pair of hits at the top of the UCSD order, combining for three RBI and a run as Shirley drove in the two on his triple and scored.

Making his first career start, Sonoma State’s Jayson Richards matched Scott zero for zero for a majority of the evening, but took the loss (2-1). He allowed just a single run on five hits and three walks over 6.1 frames.

Both teams produced a spectacular play in the outfield. Shirley lofted a high fly ball to open the home third that Seawolf leftfielder Devin Alexander virtually flew toward the foul line to snatch and prevent what likely would have been an earlier triple for the Triton. Larsen returned the favor in the sixth, tracking back toward the wall in straightaway center to stretch and snare Eric Ehlow’s hard-hit drive.

Triton Notes:Troy Cruz is the only Triton to start all 50 games, with 12 coming on the mound ... Erik Lewis extended his reached-base streak to 19 games and hit streak to seven, both current team bests ... Lewis produced his team-leading 20th multi-hit contest ... With his first-inning walk, Nick La Face is now just one shy of matching Aaron Bauman’s single-season program record of 45 (2010) ... Since the start of April, Garrett Tuck is hitting .350 (21-for-60) with 11 runs, a double, triple and 11 RBI ... The Tritons are 16-7 at home in 2014 and 22-4 over their last 26 ... UCSD has seven shutouts this season ... The Tritons improved to 16-12 all-time in the NCAA Division II Championship, making their seventh appearance, and are 2-3 against Sonoma State.